[ubuntu] Testing USB pen drive with poor write speeds

[ubuntu] Testing USB pen drive with poor write speeds

Hello all,

So i have this SanDisk Ultra Trek 64GB pen drive (USB 3.1) and I’m thinking of getting another but first I’m testing the write speed as many reviews I read before I bought it said that the write speed degrades massively over a relatively short period. I’ve already tested it once using the ‘dd’ utility, and the results were pretty poor, so I wanted to check the method I used was good. The method in question is basically what is found on linuxconfig.com

  1. First I used ‘fdisk’ to remove all partitions and created a single ‘Linux’ partition (not sure what Linux means in this context but it seemed the obvious choice)
  2. ran ‘sudo mkfs -t ext4 /dev/sda1’
  3. ran ‘sudo dd if=/dev/zero of=/dev/sda1 oflag=direct bs=128k count =32k

below is a copy of dd’s output…


32768+0 records in
32768+0 records out
4294967296 bytes (4.3 GB, 4.0 GiB) copied, 527.162 s, 8.1 MB/s

…I know there are many variables here and SanDisk probably didn’t specify the write speed in the context of Linux, but they claim read speeds up to 130MB/s with write speeds “lower”, significantly lower by the looks of my 8.1MB/s. It is in a blue USB type A port which I believe denotes the USB 3.1 standard?

For reference I have the most awful USB pen drive on earth that came as part of one of those promotional pens that companies hand out with their branding on, it doesn’t even look like an electronic device and is easily ten years old, and after undergoing the same procedure plugged into the same port it was getting write speeds of 11MB/s plus.

The only steps I omitted that the guide recommends were to run the ‘sync’ command and also to run ‘echo 3 > /proc/sys/vm/drop_caches’. I didn’t use the former because I believe the ‘dd’ option ‘oflag=direct’ means caching isn’t used, and the latter because I don’t know what it does (also I cant use ‘cat’ to view the contents of that pseudo file, even with sudo, so I left it be).

Any critique is welcome!

Edit: From SanDisks Website –

“Most of the SanDisk USB flash drives fall under the entry level category unless otherwise labeled as Ultra or Extreme. Entry level USB drives do NOT have any defined transfer speed. The Ultra and Extreme USB flash drives transfer speed MAY vary from 10MB/s to 260MB/s depending on the specific product.”

So, maybe it’s normal? I’m still unsure…


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